On the Basis for the Agrammatic's Difficulty in Producing Main Verbs

Abstract

Current theories of agrammatism do not provide a clear explanation for the co-occurrence of omission of grammatical markers and main verbs in this disorder. This study tested the hypothesis that the two symptom features have distinct underlying causes. Specifically, that the omission of main verbs in agrammatic speech is caused, at least in part, by a lexical (as opposed to a syntactic) deficit. Agrammatic and anomic aphasics and normal controls were given an object and action naming test. Agrammatic patients showed a marked impairment in naming actions in contrast to anomic aphasics and normal controls who named actions better than objects. The action naming impairment in agrammatic patients was interpreted as evidence for the lexical deficit hypothesis of verb omission in the speech of these patients and as a demonstration that agrammatism is a heterogeneous disorder that implicates damage to both lexical and syntactic mechanisms.

Lexical, Morphological, and Syntactic Aspects of Verb Production in Agrammatic Aphasics

“…If these aphasics suffer from retrieval problems for verbs, as is often suggested in the literature (e.g. Cheng & Bates, 1998;Miceli, Silveri, Villa, & Caramazza, 1984;Zingeser & Berndt, 1990), then a frequency effect might be expected. Although a frequency effect has often been shown for retrieval deficits for nouns, it has been mentioned before that such an effect for verbs does not exist (see, e.g., Jonkers, 1998).…”

Grammatical processing of nouns and verbs in left frontal cortex?

“…As we mentioned in the Introduction, several studies in the neuropsychological literature have described patients who have greater difficulty producing verbs than nouns [4,6,9,32,35]. However, at least some of these putative verb impairments seem to be of a very different type than the deficit exhibited by R.C.…”

“…1 and 2). Numerous neuropsychological [10,22,23,31,49] and neuroimaging [7,14,15,18,35] studies have implicated these regions in grammatical processing and computation of morphological agreement.…”

“…Some patients are poor at naming verbs relative to nouns [4,6,9,33,35], while others are worse at naming nouns than verbs [2,35,47,56]. But these deficits have most often been interpreted as resulting from damage to sensorimotor networks that store or mediate access to conceptual knowledge about objects and actions [12,43,54].…”

Unaccusative verb production in agrammatic aphasia: the argument structure complexity hypothesis

“…Verb production; Unaccusatives; Syntactic deficits; Agrammatism It has been well documented in the literature that some individuals with aphasia, particularly those showing deficit patterns consistent with a diagnosis of Broca's aphasia with agrammatism, evince greater difficulty producing verbs as compared to nouns (Berndt, Mitchum, Haendiges, & Sandson, 1997; Miceli, Silveri, Nocentini, & Caramazza, 1988;Miceli, Silveri, Villa, & Caramazza, 1984; Thompson et al, l995b;Zingeser & Berndt, 1990). While recent research focused on determining the nature of verb production deficits has shown that several factors may play a role in this production difficulty, including frequency and familiarity (Kemmerer & Tranel, 2000), imageability (Bird, Howard, & Franklin, 2000), and semantic factors (Breedin, Saffran, & Schwartz, 1998), the number of syntactic arguments associated with the verb and corresponding participant roles has been shown to influence verb production in several studies (Jonkers & Bastiaanse, 1996Kegl, 1995;Kemmerer & Tranel, 2000;Kim & Thompson, 2000;Kiss, 2000 Lange, Schneider, & Shapiro, 1997; Thompson, Shapiro, Li, & Schendel, 1995a).…”